New clinical study confirms that beans are the preferred starch source for diabetics

I have taught for years that beans are nutritionally superior to whole grains, and should be the preferred starch source for diabetics – I often call my dietary recommendations for diabetics “the greens and beans diet” (learn more in my new book The End of Diabetes) A study published by the research group of Dr. David Jenkins (who originally developed the concept of the glycemic index) has confirmed the advantages of beans over whole grains, especially for diabetics.1

Beans. Flickr: cookbookman 17

One-hundred twenty-one type 2 diabetics were split into two groups; a “low-glycemic index legume diet,” which emphasized beans and other legumes, and a “high wheat fiber diet,” which emphasized whole wheat foods and other whole grains. The bean group was instructed to consume 1 cup/day of beans, lentils, or other legumes and the grain group was instructed to consume an equivalent amount of a cooked whole grain or whole wheat bread, pasta or cereal daily for three months.

The table below summarizes the changes that occurred over the three-month period in each group, and whether the improvement in the bean group was significantly greater than that in the grain group:

  Grain Group Bean Group Greater improvement in bean group?
Fiber intake (g/1000 calories) +1.9  +10  Yes 
Glycemic load of overall diet -5  -48  Yes 
HbA1c  -0.3% -0.5%  Yes 
Body weight (lbs.) -4.4  -5.7  Yes 
Fasting blood glucose (mg/dl) -7  -9  Yes 
Triglycerides (mg/dl) -9  -21  Yes 
Total cholesterol (mg/dl) -2  -9  Yes
Systolic blood pressure (top number, mmHg) No change -4  Yes 
Diastolic blood pressure (bottom number, mmHg)  No change -3 Yes 
Heart rate (beats/minute) -0.6  -3.4  Yes 
10-year Framingham coronary heart disease risk score  -0.5 -1.1  Yes 


Fiber and Glycemic load (GL)
As you can see from the table, the bean group’s fiber intake increased more and GL decreased dramatically more compared to the grain group. This highlights important nutritional differences between beans and whole grains. When it comes to fiber content, even intact whole grains don’t even come close to beans. Plus, much of the starch in beans is resistant starch and slowly digestible starch, which limits the overall glycemic effect of the carbohydrate in beans and are fermented into anti-cancer compounds in the colon. Beans are also higher in resistant starch than most grains.

Glycemic control
Hemoglobin A1c, or HbA1c is a measure of the percentage of the hemoglobin in the blood that has been glycated (has had a sugar molecule added to it); the higher your blood glucose, the more glycation occurs. The HbA1C result is an indicator of blood glucose levels over the previous three months. After three months on the bean-enriched or grain-enriched diets, this measure of long-term glycemic control was improved in both groups, but a greater improvement was seen in the bean group.

Although it may seem small, a 0.5% decrease in HbA1C is actually quite large, considering that a “healthy” (nondiabetic) A1C is below 6.0%, and a poorly controlled diabetic level is 8.0% or higher. The authors note that A1C reductions in the range of 0.5-1% translate into significant risk reductions for complications such as kidney damage.3,4 A small improvement in HbA1c (like the half-point improvement here) is very significant, as it could represent years of lifespan gained or lost. Beans as the major starch source in the diet have the potential to make a huge positive impact on the long-term health of diabetics.

These improvements in health are cumulative with other dietary changes that improve HbA1c. So a small improvement from more beans and squashes, comes with a small improvement from berries and greens, and an small improvements from using nuts and seeds, and a small improvement from not snacking and so on, and all these small improvements which at first may seem like just a few tenths in HbA1c cumulatively result in massive benefits and for most, the end of diabetes.

Blood pressure and heart disease risk
People who eat more beans tend to have lower blood pressure (not to mention greater fiber and mineral intake, lower body weight, and smaller waist circumference).5 Beans are rich in fiber (especially soluble fiber) and minerals, and low in GL – characteristics that have anti-hypertensive effects.1,6-10

The decrease in blood pressure in the bean group significantly improved their calculated Framingham risk score, an estimate of heart disease risk over the next ten years. This is an extremely important point, since most diabetics die of heart disease or stroke.11

Comparing two healthful food groups: grains are good, beans are better.
When diabetics switch from white flour, sugar and white rice to whole grains, they get significant health benefits. Plus, even when they switch from white potato to whole grains they get significant glycemic and other benefits, since whole grains have a comparatively lower glycemic index and more fiber than white potato.12

This study shows that when diabetics rely on beans as their primary carbohydrate source, they get even more benefits than with whole grains; more evidence of how special beans are – their nutritional superiority as a carbohydrate source.

In the End of Diabetes reversal program, when choosing carbohydrate sources I recommend:

  • No white flour, white rice or white potato
  • Small amounts of whole grains
  • More kiwi, berries, pomegranate, squash and beans

Of course, these carbohydrate sources are consumed in conjunction with plentiful low-calorie vegetables – greens, eggplant, onions, mushrooms, tomatoes, etc. , plus nuts and seeds daily for a phytochemical-rich, low-glycemic dietary profile with substantial anti-cancer and cardiovascular benefits.


1. Jenkins DJ, Kendall CW, Augustin LS, et al: Effect of Legumes as Part of a Low Glycemic Index Diet on Glycemic Control and Cardiovascular Risk Factors in Type 2 Diabetes Mellitus: A Randomized Controlled Trial. Arch Intern Med 2012:1-8.
2. Sievenpiper JL, Kendall CW, Esfahani A, et al: Effect of non-oil-seed pulses on glycaemic control: a systematic review and meta-analysis of randomised controlled experimental trials in people with and without diabetes. Diab tologia 2009;52:1479-1495.
3. Patel A, MacMahon S, Chalmers J, et al: Intensive blood glucose control and vascular outcomes in patients with type 2 diabetes. N Engl J Med 2008;358:2560-2572.
4. Stratton IM, Adler AI, Neil HA, et al: Association of glycaemia with macrovascular and microvascular complications of type 2 diabetes (UKPDS 35): prospective observational study. BMJ 2000;321:405-412.
5. Papanikolaou Y, Fulgoni VL, 3rd: Bean consumption is associated with greater nutrient intake, reduced systolic blood pressure, lower body weight, and a smaller waist circumference in adults: results from the National Health and Nutrition Examination Survey 1999-2002. J Am Coll Nutr 2008;27:569-576.
6. Streppel MT, Arends LR, van 't Veer P, et al: Dietary fiber and blood pressure: a meta-analysis of randomized placebo-controlled trials. Arch Intern Med 2005;165:150-156.
7. Houston MC: The importance of potassium in managing hypertension. Curr Hypertens Rep 2011;13:309-317.
8. Houston M: The role of magnesium in hypertension and cardiovascular disease. J Clin Hypertens (Greenwich) 2011;13:843-847.
9. DeFronzo RA, Cooke CR, Andres R, et al: The effect of insulin on renal handling of sodium, potassium, calcium, and phosphate in man. J Clin Invest 1975;55:845-855.
10. Chiasson JL, Josse RG, Gomis R, et al: Acarbose treatment and the risk of cardiovascular disease and hypertension in patients with impaired glucose tolerance: the STOP-NIDDM trial. JAMA 2003;290:486-494.
11. American Diabetes Association: Diabetes statistics []
12. Halton TL, Willett WC, Liu S, et al: Potato and french fry consumption and risk of type 2 diabetes in women. Am J Clin Nutr 2006;83:284-290.



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Comments (7) Read through and enter the discussion with the form at the end
AmyLu - December 21, 2012 8:28 PM

If a diabetic already has significant kidney damage (function is 27 percent) and he is consequently limiting potassium intake, could he safely eat beans?

carfree - December 22, 2012 2:49 PM

Although the chart says the bean group did not experience greater cholesterol control than the grain group, the numbers seem to indicate that they did. Should that have been a +9 rather than a -9?

Matt Ahrens - December 22, 2012 8:08 PM

I read somewhere that pumpernickel and light rye were better than whole wheat. I'm guessing other whole grains are superior to whole wheat too.

Joel Fuhrman, M.D. - December 24, 2012 1:44 PM

In reference to kidney disease, the precise recommendations has to consider your blood test for potassium and this is best answered byyour physician, or by our medical staff in the Ask The Doctor forum in the member center, after reviewing your total diet and blood work.

Deana Ferreri, PhD - December 24, 2012 1:48 PM

Carefree, -9 is correct. The difference was listed as not significant in error, and has now been corrected.

Scott @ The Healthy Eating Guide - December 26, 2012 9:57 PM

This is interesting and important information. Beans are a true superfood that most folks would really benefit from eating more of, as evidenced by this study. I'll be pointing my friends, especially those suffering from diabetes, to this article.

B J - January 28, 2013 10:07 PM

Your blog was very informative about superfoods like beans that can improve our health. My brother in law has a family history of diabetes and he also has changed his diet by eating more natural and organic foods. He cooked beans this weekend for his family. Thanks again for this update on how to help those with diabetes.

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